Oilfield fluids (e.g., oil, gas, and water) are generally complex mixtures of aliphatic hydrocarbons, aromatics, hetero-atomic molecules, anionic and cationic salts, acids, sands, silts, clays and a vast array of other components. The nature of these fluids, combined with the severe conditions of heat, pressure, and turbulence to which they are often subjected, are contributory factors to the formation and deposition of contaminants, such as scales, salts, paraffins, corrosion, bacteria and asphaltenes in oil and/or gas production wells. Such contaminants also form in equipment and flow conduits used in gas production and oil production as well as in refineries and fluid processing facilities.
A common site for the formation and deposition of such contaminants in oil or gas wells is the annular space between the production tubing and casing. The annulus may be a static area or may produce gas or liquid. In low pressure gas wells, such as coal bed methane wells, the gas is produced up the annulus and the liquid (water) is allowed to fall to the liquid level and removed via a submersible pump up the tubing. Such undesirable substances as salt, scales, paraffins and asphaltenes form due to the pressure changes at the perforations. Alternatively, such substances form due to commingling of incompatible waters from one set of perforations to another. The formation and deposition of such contaminants decrease permeability of the subterranean formation and reduce well productivity. For instance, in some completions, the presence of scale in the annulus may make it difficult or impossible to remove the tubing for servicing.
In addition to being formed in oil and gas wells, such contaminants further form in equipment and flow conduits used in the production of oil, gas and other fluids. For instance, an acute problem develops when such contaminants develop in equipment and flow conduits used in gas and oil production, refineries and other fluid processing facilities.
While there are a number of approaches to the inhibition and/or removal of contaminants in the patent and journal literature, nearly all of them deal with the problem on an individual basis as they form, which can be costly when numerous problems arise during operations. A further problem with such an approach is the cost of tracking and monitoring the effectiveness of the selected approach.
For example, in oil and gas production, the technique of “downhole squeezing” is commonly used to address oil field scale formation, wherein a slug of the treatment composition is injected into the annulus, using a pre-flush, squeeze, and overflush treatment before the well can be returned to normal function. However, the overflush process often flushes a significant portion of the treatment agent such the remaining treatment agent is gradually removed from the surface as oil production continues. Thus, further descaling treatments are typically required.
Treatment methods of the prior art are typically inefficient in that contact with all surfaces containing the contaminants is typically required though often not completely attained. In addition, large quantities of the treatment agent are often required in order to effectuate the desired result.
Alternative treatment methods have therefore been sought for introducing treatment agents into oil and/or gas wells as well as equipment and flow conduits used in the production of oil and gas as well as equipment and flow conduits used in refineries and fluid processing facilities.